Metal shears



A. AAPRO July 9, 1963 METAL SHEARS Filed March 9, 1961 NYEN 43% 1W United States Patent Oflice 3,096,581 Patented July 9, 1963 3,096,581 METAL SHEARS Antti Aapro, Downsview, Ontario, Canada Canadian Research & Development Foundation, 1434 Queen St. W., Toronto 3, Ontario, Canada) Filed Mar. 9, 1961, Ser. No. 94,553 2 Claims. (Cl. 30-261) This invention relates to improvements in sheet metal cutting devices, and more particularly to improvements in hand operated sheet metal shears.

It is conventional practice to utilize scissor type shears in the cutting of sheet metal, having the disadvantage that a deep cut beyond the pivot point of the blades requires that the metal be bent upwardly and downwardly to avoid the shoulders of the blades. It is also very difiicult to open the blades up once they have closed in on a cutting stroke. Spring devices have been fitted to assist in the opening action, having the disadvantage that the pressure of the spring must also be overcome during the cutting action. With this type of shears, also, it is necessary to have a separate means for locking the blades in a closed position when not in use.

It is also conventional practice to utilize chisel and hammer means to make a hole in a sheet of metal, upon commencing a cut which does not extend to the edge of the material, having the disadvantage that chisels are often mislaid and, in many cases where the sheet metal is of such a size that the operator must stretch in order to reach the starting point, he may quite easily miss-hit, damaging either his fingers or the sheet of metal.

It is an object of this invention to provide a pair of sheet metal shears that will distort the sheet very little during the cutting process.

It is another object of this invention to provide sheet metal shears that will give a spring loaded assistance both in opening the blades and in closing them.

It is a further object of this invention that the spring loaded assistance for both opening and closing the blades should be embodied in one unit.

It is yet another object of this invention to provide a pair of sheet metal shears which, by utilzing the previously mentioned spring loaded assistance, may be kept in the closed position when not in use.

It is a further object of this invention to provide a pair of sheet metal shears having a chisel member in combination therewith, thereby extending an operators reach by the length of the shears and, by eliminating the danger of crushed fingers, enabling him to make a cleaner, harder blow.

These and other objects and features of this invention will become apparent when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a fractional, part sectional, side elevation of a pair of metal shears embodying this invention, showing the jaws in the open position.

FIG. .2 is a fractional, part sectional, side elevation of a pair of shears embodying this invention as shown in FIG. 1, having the jaws in the closed position.

FIG. 3 is a sectional end elevation of the shears illustrated in FIG. 1 taken on the line 3-3.

FIG. 4 is a fractional, side elevation of the grip portion of a pair of shears embodying this invention illustrating the chisel attachment.

Referring to FIGS. 1 and 2, a pair of shears, indicated generally by arrow 10, comprise a horizontal blade 11 and a vertical blade -12. A lever 13 extends upwardly at substantially right angles from the rear of one side of horizontal blade 11 and subsequently extends substantially at right angles rearwardly therefrom to form a handle portion 14. Lever 13 is flat and carries a pivot pin '15 therethrough.

Vertical blade 12 continues rearwardly to form a handle 16 adapted to be swivelably attached to handle 14 by pivot pin 15. The opening and closing of handles 14 and 16, therefore, results in an opening and closing of blades -11 and 12, the innermost edges of blades 11 and 12 being cutting edges in the conventional, shearing manner.

A spring loaded ram assembly, indicated by arrow 17, comprises an outer cylindrical body 18, having an open end 19 and a closed end20', a coil spring 21 being contained therein and held in compression by a cylindrical ram 22 adapted to be a sliding fit within outer body 18.

Ram 22 is pivotally attached to handle portion 16, and the closed end 20 of outer body 18 is bifurcated to form two side pieces 23 adapted to retain between them the rear edge of the vertical lever 13. A pin 24 passes laterally through side pieces 23 and is adapted to engage either an upper notch 25 or a lower notch 26 formed in the rear edge of lever 13. Upper notch 25 is located above pivot pin 15 and lower notch 26 is located below pivot pin 15.

Referring to FIG. 1, pin 24 of ram assembly 17 is shown engaged with upper notch 25 of lever 13. Spring 21 is in compression, ram 22 is attached to handle 16 and therefore, the pressure exerted by spring 21 causes outer body 18 to move outwardly of the assembly. This in turn causes pin 24 to exert a pressure through upper notch 25 to lever 13, and, being above pivot pin 15, the action of ram assembly 17 forces handle 14 away from handle 16 and thereby opens the blades 11 and 12.

Referring to FIG. .2, having reached the position as illustrated in FIG. 1, and upon desiring assistance in closing blades 11 and 12, an operator, by grasping outer body 18 and further compressing spring 21 to permit pin 24 to move outwardly of upper notch 25, causes ram assembly 17 to move arcuately downwardly until pin 24 engages with lower notch 26. -In this position, the pressure exerted by ram assembly 17 on lever .13 is below the pivot pin 15 causing handles 14 and 1-6 to come together and thereby assisting .the operator to close blades 11 and 12.

Referring to FIG. 4, it may be seen that lower handle 16 extends rearwardly a greater distance than upper handle 14 and terminates in a boss 27. A chisel assembly 28' passes vertically through boss 27 and comprises an anvil portion 29 extending upwardly from boss 27 and a chisel portion 30 extending downwardly therefrom. Sufficient gap exists between the end of handle 14 and anvil portion 29 to permit an operator to strike anvil 29 with a hammer without striking handle 14.

The method of utilizing a pair of sheet metal shears embodying this invention is as follows. Having the shears in a closed position as illustrated in FIG. 2, the operator grips blades 11 and 12 in the one hand and places chisel assembly 28 in the desired position on the sheet metal. Holding shears assembly 10 so that chisel assembly 28 is vertical, the operator strikes :anvil 29 until chisel portion 30 has made a hole big enough to insert blade 11. By adjusting ram assembly 17 so that pin 24- is in notch 25, blades 11 and 12 are forced open and blade 11 is able to be positioned on the underside of the sheet metal. The operator then moves ram assembly 17 to its lower position in which pin 24 engages with lower notch 26 and then, having the assistance of ram assembly :17 in closing handles 14 and 16, he is able to close blades 11 and 12 thereby cutting the sheet metal.

Those skilled in the art know that it is often as diflicult to open shears once the cutting action has taken place as it is to cut the metal, and, therefore, by moving ram assembly 17 so that pin 24 engages with upper notch 25 the operator may gain assistance in opening handles 14 and 16, in preparation for the next cutting action.

Upon completion of a cutting job, and prior to replacing shears 10 in his tool kit or the like, the operator may move ram assembly 17 to its lower position as illustrated in FIG. 2, thereby causing handles 14- and 16 to come together and blades 11 and 12 to be retained in the closed position by the loading of spring 21.

The general design of the individual parts of'the invention as explained above may be varied according to requirements in regards to manufacture and production thereof, while still remaining within the spirit and principle of the invention, without prejudicing the novelty thereof. a

The embodiments of the invention in which an exclusive property of privilege is claimed are defined as follows:

1. A metal shearing tool comprising in combination an upper blade and a lower blade, said upper blade having a cutting edge disposed in the vertical plane, the remaining portion of said upper blade being disposed upwardly and outwardly of said cutting edge, said lower blade having a cutting edge disposed in the horizontal plane, the remaining portion of said lower blade being disposed outwardly from said cutting edge, said upper blade and said lower blade being pivotally secured together, said pivot being .positioned substantially above the cutting line formed by said upper blade and said lower blade, said cutting edge of said upper blade being formed rearwardly and terminating substantially below said pivot point, an upper handle member secured to said lower blade, a lower handle member secured to said upper blade, said upper handle member and said lower handle member lying substantially above said cutting line and dual-position spring loaded ram means selectively adjustable to eifect either opening or closing of said blades.

'2. A metal shearing tool as claimed in claim 1 wherein said dual-position spring loadedram means comprises a spring loaded extensible member, said extensible member being pivotally secured to said lower handle member, indents formed along the inner edge of said upper handle member substantially adjacent to said pivot, said extensible member having its free end adapted to match with said indents whereby said spring loaded extensible member will bias said upper handle member about said pivot.

References Cited in the file of this patent UNITED STATES PATENTS 1,161,526 Porter NOV. 23, 1915 1,594,671 Isaac Aug. 3, 1926 1,816,056 Richard July 28, 1931 1,836,967 Helwig Dec. 15, 1931 2,648,901 Northcutt Aug. 18, 1953 FOREIGN PATENTS 431,315 Italy Feb. 25, 1948 968,073 France Nov. 17, 1950 969,327 France Dec. 19, 1950 522,418 Italy Apr. 7, 1953 

1. A METAL SHEARING TOOL COMPRISING IN COMBINATION AN UPPER BLADE AND A LOWER BLADE, SAID UPPER BLADE HAVING A CUTTING EDGE DISPOSED IN THE VERTICAL PLANE, THE REMAINING PORTION OF SAID UPPER BLADE BEING DISPOSED UPWARDLY AND OUTWARDLY OF SAID CUTTING EDGE, SAID LOWER BLADE HAVING A CUTTING EDGE DISPOSED IN THE HORIZONTAL PLANE, THE REMAINING PORTION OF SAID LOWER BLADE BEING DISPOSED OUTWARDLY FROM SAID CUTTING EDGE, SAID UPPER BLADE AND SAID LOWER BLADE BEING PIVOTLLY SECURED TOGETHER, SAID PIVOT BEING POSITIONED SUBSTANTIALLY ABOVE THE CUTTING LINE FORMED BY SAID UPPER BLADE AND SAID LOWER BLADE, SAID CUTTING EDGE OF SAID UPPER BLADE BEING FORMED REARWARDLY AND TERMINATING SUBSTANTIALLY BELOW SAID PIVOT POINT, AN UPPER HANDLE MEMBER SECURED TO SAID LOWER BLADE, A LOWER HANDLE MEMBER SECURED TO SAID UPPER BLADE, SAID UPPER HANDLE MEMBER AND SAID LOWER HANDLE MEMBER LYING SUBSTANTIALLY ABOVE SAID CUTTING LINE AND DUAL-POSITION SPRING LOADED RAM MEANS SELECTIVELY ADJUSTABLE TO EFFECT EITHER OPENING OR CLOSING OF SAID BLADES. 